The present invention relates to a method of removing wrinkles from a superficial area of mammalian skin tissue.
The application of laser technology in healthcare is well known, and the use of lasers in medical applications has been studied extensively since the early 1960's. In recent years an increasing interest has been shown in cosmetic applications. One such cosmetic application is skin resurfacing and wrinkle removal; in this field lasers can be used as an alternative to surgical facelifts. A CO.sub.2 laser, which operates in the infra-red region of the spectrum, is used, the radiation being totally absorbed in a thin layer of surface tissue, primarily because of the wavelength's high rate of absorption in water.
The current approach used to achieve CO.sub.2 laser based skin resurfacing and wrinkle removal involves a two stage process, as follows:
Stage 1--Skin Resurfacing: The purpose of the first stage is to remove a thin layer of tissue from a superficial area of mammalian skin tissue. To achieve this, the skin is irradiated by the laser which, as mentioned above, deposits its energy in a thin layer at the surface (approx 30 .mu.m in thickness). The application of the laser radiation to the tissue is by computer controlled scanner designed to ensure that one pass of the radiation removes one "layer" of tissue only. In this way, damage is limited to the epidermis only. This process quickly ablates the surface layer removing the surface skin and with it any skin blemishes. The process is straightforward and does not demand a great deal of operator skill. The surface skin immediately starts to replace itself and this allows the skin to return to normal in about 3 to 5 days.
Stage 2--Wrinkle Removal: After the skin surface has been resurfaced, the operator will, typically, apply further "passes" of the laser, thereby removing further layers of mammalian skin tissue, each layer being of the order of 30 .mu.m thick. Typically, around three or four further passes will complete the wrinkle removal procedure. This treatment therefore produces a controlled second degree burn. The skin barrier to the outside world is removed and therefore, there is a danger of infection.
The required effect is two fold:
(a) the laser induces denaturing of the collagen in the dermis, and the formation of cross links, which results in a tightening effect stretching the skin, reducing or removing the wrinkles (it is thought that the thermal threshold for this effect is a temperature of 70.degree. C.); and PA1 (b) the changes to the dermis induce the generation of new collagen which develops using the matrix created by the denatured collagen as a foundation.
The skin-resurfacing and wrinkle removal procedure outlined above is considered by many experts in the field as a significant improvement over previously used surgical methods. The procedure uses the laser's ability to deliver high energy density at the surface of tissue and hence ablate the surface tissue in a well controlled manner. Continuing to remove the tissue, layer by layer is designed to damage the collagen and hence induce wrinkle removal. This second stage of the procedure is primitive; the skin weeps, scabs form and redness of the skin appears for many weeks.